For the original Cities: Skylines on Steam, test once with Paradox's exact launch options -noWorkshop -disableMods. If the game starts, isolate Workshop content. If it still fails, remove the options and use the game's output log to choose the next fix instead of deleting saves or reinstalling blindly.
These steps are for the original Cities: Skylines on Steam, not Cities: Skylines II. Record whether it fails before the launcher, after selecting Play, while loading a city, or only with one save.
2
Keep saves and current launch options
Do not delete saves, subscribed assets, or configuration folders. Open the Steam launch-options field and copy any existing value somewhere private so you can restore it after this test.
3
Enter Paradox's mod-free launch options
In Steam Library, open Cities: Skylines Properties and place -noWorkshop -disableMods in Launch Options exactly as Paradox documents. These options test whether Workshop assets or mods are involved without unsubscribing from them.
Start the game once. If it reaches the menu, test a new empty city before opening an important save. If the game works with these options, a Workshop mod or asset is the likely cause.
5
Isolate custom content if the game starts
Exit the game, remove the temporary options, then disable or re-enable mods and assets in small groups until the failure returns. Keep the last working group recorded instead of changing the entire collection at once.
6
Use the output log if it still fails
If the game still fails with both launch options, remove them and inspect the output_log.txt location linked by Paradox. Match a specific exception, memory message, or named component before acting on it; do not assume every crash has the same cause.
7
Verify files and test again
Use Steam's Verify integrity of game files control, wait for completion, then test once with the same save or startup path. Keep the resulting output log if the crash returns.
Only follow Paradox's Citrix Workspace or memory and page-file instructions when the output log names the matching problem. Those fixes do not apply to every crash.
If one save crashes while a new city works, keep the affected save and output log for Paradox Support. Do not overwrite the save with a test session or remove large asset groups without a record.
ⓘ Sources and verification
Checked against official documentation on . Scope: Platform not recorded.
If a button or setting has moved after an update, use the linked official help page to find its current location.
